ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 101 insertions, 0 deletions

diff --git a/drivers/pmdomain/st/Kconfig b/drivers/pmdomain/st/Kconfig
new file mode 100644
index 000000000..a77a70211
--- /dev/null
+++ b/drivers/pmdomain/st/Kconfig
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config UX500_PM_DOMAIN
+	bool "ST-Ericsson ux500 Power Domain"
+	depends on ARCH_U8500 || COMPILE_TEST
+	default ARCH_U8500
diff --git a/drivers/pmdomain/st/Makefile b/drivers/pmdomain/st/Makefile
new file mode 100644
index 000000000..6d8b617eb
--- /dev/null
+++ b/drivers/pmdomain/st/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_UX500_PM_DOMAIN)		+= ste-ux500-pm-domain.o
diff --git a/drivers/pmdomain/st/ste-ux500-pm-domain.c b/drivers/pmdomain/st/ste-ux500-pm-domain.c
new file mode 100644
index 000000000..6896cb4a7
--- /dev/null
+++ b/drivers/pmdomain/st/ste-ux500-pm-domain.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2014 Linaro Ltd.
+ *
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * Implements PM domains using the generic PM domain for ux500.
+ */
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/pm_domain.h>
+
+#include <dt-bindings/arm/ux500_pm_domains.h>
+
+static int pd_power_off(struct generic_pm_domain *domain)
+{
+	/*
+	 * Handle the gating of the PM domain regulator here.
+	 *
+	 * Drivers/subsystems handling devices in the PM domain needs to perform
+	 * register context save/restore from their respective runtime PM
+	 * callbacks, to be able to enable PM domain gating/ungating.
+	 */
+	return 0;
+}
+
+static int pd_power_on(struct generic_pm_domain *domain)
+{
+	/*
+	 * Handle the ungating of the PM domain regulator here.
+	 *
+	 * Drivers/subsystems handling devices in the PM domain needs to perform
+	 * register context save/restore from their respective runtime PM
+	 * callbacks, to be able to enable PM domain gating/ungating.
+	 */
+	return 0;
+}
+
+static struct generic_pm_domain ux500_pm_domain_vape = {
+	.name = "VAPE",
+	.power_off = pd_power_off,
+	.power_on = pd_power_on,
+};
+
+static struct generic_pm_domain *ux500_pm_domains[NR_DOMAINS] = {
+	[DOMAIN_VAPE] = &ux500_pm_domain_vape,
+};
+
+static const struct of_device_id ux500_pm_domain_matches[] = {
+	{ .compatible = "stericsson,ux500-pm-domains", },
+	{ },
+};
+
+static int ux500_pm_domains_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct genpd_onecell_data *genpd_data;
+	int i;
+
+	if (!np)
+		return -ENODEV;
+
+	genpd_data = kzalloc_obj(*genpd_data);
+	if (!genpd_data)
+		return -ENOMEM;
+
+	genpd_data->domains = ux500_pm_domains;
+	genpd_data->num_domains = ARRAY_SIZE(ux500_pm_domains);
+
+	for (i = 0; i < ARRAY_SIZE(ux500_pm_domains); ++i)
+		pm_genpd_init(ux500_pm_domains[i], NULL, false);
+
+	of_genpd_add_provider_onecell(np, genpd_data);
+	return 0;
+}
+
+static struct platform_driver ux500_pm_domains_driver = {
+	.probe  = ux500_pm_domains_probe,
+	.driver = {
+		.name = "ux500_pm_domains",
+		.of_match_table = ux500_pm_domain_matches,
+	},
+};
+
+static int __init ux500_pm_domains_init(void)
+{
+	return platform_driver_register(&ux500_pm_domains_driver);
+}
+arch_initcall(ux500_pm_domains_init);